Blocking in replication

Hi All
I am having transactional replication setup over databases upto 1 TB.
Where can I get information about troubleshooting blocking issue between replication distribution cleanup and agent history cleanup jobs. Both the agents are executing every 10 mins. However, they frequently raise blocking alarms on the server.
If anyone can provide some good links or advise on how to troubleshoot this.

Keeping away the size of database, I would say that the blocking is happening because of the code that is used and while performing the replication snapshot such blocking & locking is happening.
Check the default value for MAX_DISCRETION from SSMS --> Replication --> Distributors properties -->Transaction retention.